a) Field of the Invention
The present invention relates to cooling system (or, apparatus) and method for a stepping motor which drives a shift control valve for controlling hydraulic pressure that is supplied to pulleys of a belt-type continuously variable transmission.
b) Description of the Related Art
As a continuously variable transmission that is suitable for an automotive vehicle, there is a belt-type continuously variable transmission using a V-belt (hereinafter, also called a belt-CVT). A Japanese patent application B2 publication No. H03(1991)-72863 published on Nov. 20, 1991 exemplifies a configuration of a belt-CVT. Usually, a belt-CVT includes an oil pan which serves to store working fluid used for lubricating various parts and driving a forward/backward switching mechanism (or, unit) and pulleys. A previously proposed stepping motor cooling system for a belt-type continuously variable transmission cools heat generated in the stepping motor in such a way that the stepping motor is disposed within the stored working fluid.